若两个等差数列{an}、{bn}的前n项和分别为An、Bn,且满足An\Bn=4n+2\5n-5,则a5+a13/b5+b13的值为?
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![若两个等差数列{an}、{bn}的前n项和分别为An、Bn,且满足An\Bn=4n+2\5n-5,则a5+a13/b5+b13的值为?](/uploads/image/z/13570724-20-4.jpg?t=%E8%8B%A5%E4%B8%A4%E4%B8%AA%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%7Ban%7D%E3%80%81%7Bbn%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%E5%88%86%E5%88%AB%E4%B8%BAAn%E3%80%81Bn%2C%E4%B8%94%E6%BB%A1%E8%B6%B3An%5CBn%3D4n%2B2%5C5n-5%2C%E5%88%99a5%2Ba13%2Fb5%2Bb13%E7%9A%84%E5%80%BC%E4%B8%BA%3F)
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若两个等差数列{an}、{bn}的前n项和分别为An、Bn,且满足An\Bn=4n+2\5n-5,则a5+a13/b5+b13的值为?
若两个等差数列{an}、{bn}的前n项和分别为An、Bn,且满足An\Bn=4n+2\5n-5,则a5+a13/b5+b13的值为?
若两个等差数列{an}、{bn}的前n项和分别为An、Bn,且满足An\Bn=4n+2\5n-5,则a5+a13/b5+b13的值为?
由题,A17/B17=70/80=7/8=17a9/17b9,故:a9/b9=7/8 所以:(a5+a13)/(b5+b13)=2a9/2b9=a9/b9=7/8